1. Field of the Invention
The present invention relates to a fuel cell and a method of producing the same.
2. Description of the Related Art
Fuel cells are known which includes single cells each including a membrane electrode assembly having electrode catalytic layers and gas diffusion layers on both surfaces of a solid polymer electrolytic membrane, respectively, the membrane electrode assembly being sandwiched between a pair of separators having fluid passages for reaction gases. The fuel cell generates electric power through an electrochemical reaction between oxygen in air supplied to the electrode catalytic layer on the cathode and hydrogen in a fuel gas supplied to the electrode catalytic layer on the anode in which water is generated during the electric power generation. In the fuel cell, both the supplied air and hydrogen (reaction gases) are humidified for improvement in an ion conductivity in the solid polymer electrolytic membrane. If water generated by the electrochemical reaction and the humidification impedes flows of the reaction gases, an electric power generation capability of the fuel cell decreases.
In order to improve drainage, JP 2002-298871A proposed a fuel cell in which outlets of flow passages of reaction gases are subject to a hydrophilic treatment. JP 2005-93243A proposes a fuel cell subjected to a hydrophilic process at a part of a gas diffusion layer, forming the membrane electrode assembly, which is not overlapped with the electrode catalytic layer and near an outlet of the fluid passage of the reaction gas. JP 2004-22254A proposes a fuel cell in which the gas diffusion layers are subjected to a hydrophobic treatment at the gas diffusion layers to prevent water from penetrating the gas diffusion layers.